-LRB- CNN -RRB- -- An 11-year-old Pennsylvania boy is missing in Egypt , according to the boy 's family .

The family says that the boy 's Egyptian father abducted him .

A U.S. Embassy spokeswoman in Cairo , meanwhile , says U.S. authorities are `` aware of the situation '' and are assisting the boy 's mother in her search efforts .

Stephano Khalil Mohamed Atteya , or Nikko as he is called by his family , went to Egypt with his mother and her sister to visit his father , who lives there , according to a missing person report from the Pennsylvania State Police in Harrisburg . The boy was last seen August 1 with his father , the boy 's family said .

The father sped off with the boy in a car after forcing the boy 's mother and aunt from the car , the family said .

`` They heard -LRB- Nikko -RRB- screaming from the window , calling for his mom , '' said Nikko 's aunt , Olga Panagos , who lives in Fayetteville , Pennsylvania . `` That 's the last time they saw him . ''

Nikko 's father , an Egyptian citizen , requested that his son come to Egypt to meet his grandmother and attend his father 's sister 's wedding , American relatives said .

The U.S. Embassy in Cairo is working with Nikko 's mother , who is still in Cairo , and with local authorities to help locate the boy , according to spokeswoman Elizabeth Colton .

The boy 's parents were married in 1999 and divorced in 2005 ; Nikko was their only child together and was born in the United States , according to Panagos .

`` The family is very stressed . We have no idea where Nikko is , '' Panagos said .

Sen. Bob Casey , D-Pennsylvania , also is working with the family to provide any appropriate assistance , according to Casey spokeswoman April Melody .

CNN 's Leigh Remizowski , Mohamed Fadel Fahmy and Jill Dougherty contributed to this report .

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An embassy official in Egypt says U.S. authorities are working with the boy 's mother

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`` The family is very stressed . We have no idea where Nikko is , '' an aunt says

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The boy was in Egypt to spend time with his Egyptian father 's family